What does the letter 'k' in k-means clustering stand for?

• A. Number of Clusters
• B. Number of Groups
• C. Degree of Freedom
• D. Kernel Bandwidth

Answer: (B)

In k-means, the letter k represents the number of clusters you want to form. You choose k in advance, and the algorithm then assigns each data point to one of those k groups, updating each group's center (the centroid) as the mean of its members and iterating to minimize the sum of squared distances within clusters. So k is the count of groups (clusters) you’re forming, and changing k changes how many clusters you end up with. The other terms listed aren’t describing this concept—they come from different areas of statistics and machine learning.